Understanding historical forest condition is important as a basis for forest restoration and the development of forest management policies. White pine (Pinus strobus L.) historically has been an important commercial tree species, and significant post-settlement declines in its populations have been suggested in eastern North America since the 1600s. Logging of white pine in eastern Ontario, Canada, began in the late 1700s. We estimated the loss of white pine and changes in white pine diameter distribution in Algonquin Provincial Park by direct sampling of old stumps, censussing trees in an area that has never been harvested, assessing Crown Surveyor's records from the 1800s, using a GIS mapping technique to assess probabilistic change in pine-dominated stands, and comparing our data to other published information. Stump and tree densities since the 1800s suggested a mean reduction in the number of white pine trees of 88% from about 3 to >8 pines/ha to <1 pine/ha today in mixed and deciduous stands. GIS-based mapping predicted a maximum decline of pine-dominated stands of about 40% by area, from 539 km² that may have historically supported such forests. The diameter distribution of the current white pine trees was significantly smaller than in the historical forest (means, 44.5 cm vs. 73.4 cm, P < 0.001). Aside from early over logging, the continued low density of white pine in all forest types can be attributed in part to intense post-logging fires in the 1800s and to the past 60 years of fire suppression, which have eliminated seed sources and seedbeds. We suggest that a program using several silvicultural techniques will be necessary to restore the white pine in forest types that existed historically.